当事件需要在当前时间过后20秒执行,则该时间的“ON SHCEDULE”表达式为()
A. ON SCHEDULE 20 SECOND
B. ON SCHEDULE AT 20 SECOND
C. ON SCHEDULE AT CURRENT_TIMESTAMP +20 SECOND
D. ON SCHEDULE AT CURRENT_TIMESTAMP + INTERVAL 20 SECOND
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当事件需要在当前时间过后1小时开始执行,每6分钟执行一次,当前时间过后3小时结束,则该事件的ON SCHEDULE表达式为()
A. ON SCHEDULE AT 6 MINUTESTARTS CURRENT_TIMESTAMP +INTERVAL 1 HOURENDS CURRENT_TIMESTAMP +INTERVAL 3 HOUR
B. ON SCHEDULE EVERY 6 MINUTESTARTS CURRENT_TIMESTAMP +INTERVAL 1 HOURENDS CURRENT_TIMESTAMP+INTERVAL 3 HOUR
C. ON SCHEDULE AT 6 MINUTESTARTS CURRENT_TIMESTAMP + 1 HOURENDS CURRENT_TIMESTAMP+ 3 HOUR
D. ON SCHEDULE EVERY 6 MINUTESTARTS CURRENT_TIMESTAMP + 1 HOURENDS CURRENT_TIMESTAMP+ 3 HOUR
()是指当特定的事件(增、删、改)发生且满足相应的条件时,执行指定的操作。
激活触发器的事件有___________、___________和____________。